Three weeks ago, incoming Senate Budget Chairman Patty Murray, D-Wash., directed her staff to explore the pros and cons of actually crafting a budget resolution.

Ultimately, Murray judged that a budget was worth doing — a choice other Democratic leaders supported her on. So when House Republicans decided last week to try to force the Senate to pass a spending blueprint for the first time in three years, Democrats were ready to say yes. And on Wednesday, Murray made it official, announcing she would seek to devise a budget and saying the committee is “ready to get to work.”

The timing of Murray’s announcement was also hastened in part by Democratic Conference Vice Chairman Charles E. Schumer of New York, who spilled the beans about Democrats’ plans on TV on Jan. 20. Murray had hesitated, sources say, because the Budget Committee has not officially organized for the new Congress and she is not yet the chairwoman.

In the days before the New Year’s Day fiscal cliff deal, Murray still had not decided whether a formal budget process was the best way to articulate the Democratic Party’s position. She spent much of December in a holding pattern, but on Dec. 13, she had breakfast with the man who will be her foil — House Budget Chairman Paul D. Ryan of Wisconsin — to discuss the road ahead, her office confirmed.

So when she tasked her staff to weigh the relative benefits of developing a budget, the major question she posed was whether the formal budget process was the best vehicle for Senate Democrats to “aggressively articulate a vision while putting us potentially on a path to bring this fiscal-debt-deficit debate to a close,” one source said.

Some sources familiar with the process said the hammering Democrats have taken for not producing a budget in more than 1,000 days did not factor into the decision, but at least one senior Democratic aide said the GOP barrage was one of three major reasons for Senate Democrats’ change of heart on the matter.

“There are a number of things at play — one is the perception that the ‘Senate Democrats haven’t done a budget in x many days.’[It’s] a clumsy argument but one that people are beginning to gravitate toward,” the aide said. “And there’s an awareness of this as a message Republicans used that gained traction.”

The other major factor, of course, was political. Senate Democratic leaders’ highest priority through 2012 was maintaining their majority as they faced what they and others believed was going to be a bruising election cycle. A budget resolution is a nonbinding measure, and leaders did not want their vulnerable members to unnecessarily cast politically risky votes in the budget “vote-a-rama” that typically accompanies the Senate debate. Plus, they argued, the August 2011 debt limit deal served as an effective budget and had the force of law.

Before the debt deal was sealed in 2011, Schumer led the opposition to crafting a budget and quietly lobbied disgruntled rank-and-file members to oppose then-Chairman Kent Conrad’s push to do one.

But with Murray having helped Democrats gain two seats in November and fiscal issues dominating the talking points of both parties, sources say there are few tricky issues that could come up in a budget debate that wouldn’t come up otherwise. After all, the New Year’s fiscal cliff vote that effectively raised tax rates on higher earners is out of the way, and Democrats and Republicans recognize that Congress might have to tackle entitlement cuts in the sequester and debt limit debates, regardless of whether the Senate passes a budget.

In addition to Democrats’ willingness to take the political risks that a budget represents, sources said Senate Majority Leader Harry Reid, D-Nev., trusts Murray to keep the party’s best political interests in mind. He did not feel the same way about Conrad, a chart-loving budget wonk who seemed uninterested in the political implications of budget policy.

“Kent Conrad sucked at managing bills,” said the senior Democratic aide — unaffiliated with Murray’s office — who noted that the North Dakota Democrat was “bad at political calculations” and “a true budget policy wonk.”

“Murray is not that person,” the aide said.

As proof of his confidence, Reid publicly elevated Murray’s stature Tuesday when he referred reporters’ questions about budget matters to the new chairman.

And at a news conference Wednesday, Murray displayed a renewed assertiveness in fielding reporters’ questions, even those directed at Reid. It was as if the weight of her new gavel — and her newfound credibility as former head of the Democratic Senatorial Campaign Committee and the 2011 Joint Committee on Deficit Reduction — had redefined the unassuming “mom in tennis shoes.”

“May I answer that?” Murray interrupted Reid as he began to address the first question thrown out by a reporter.

“As I said, I intend to move forward a budget resolution through the Senate to deal with the sequestration replacement and to set appropriations levels,” Murray said. “The House Republicans can’t have it both ways. If they want us [to] — and we want to — move a budget through regular process, then they can’t have brinkmanship that they manufacture for the next six months.”